In general, Inter-Cell Interference (ICI) may occur when a limited resource, such as a frequency resource, a code resource, a timeslot resource, or etc., is divided and used for a plurality of cells in a communication system having a cellular structure (hereinafter, referred to as “cellular communication system”).
When the frequency resource is divided and used for the plurality of cells in the cellular communication system, performance is degraded due to the ICI. Here, a scheme wherein the frequency resource is divided and used for the plurality of cells is referred to as a frequency resource reuse scheme. To increase the total capacity, the cellular communication system uses the frequency resource reuse scheme. Here, the rate at which the same frequency resource is reused is referred to as a “frequency reuse factor.” The frequency reuse factor is determined by the number of cells without use of the same frequency resource. For example, when the frequency reuse factor is 1/K, the number of cells without use of the same frequency resource is K.
When the frequency reuse factor is small, that is, when the frequency reuse factor is less than 1, the ICI decreases. However, as an available frequency resource amount in one cell decreases, the total capacity of the cellular communication system decreases. Conversely, when the frequency reuse factor is 1, that is, when all cells configuring the cellular communication system use the same frequency resource, the ICI increases. However, as an available frequency resource amount in one cell increases, the total capacity of the cellular communication system increases.
On the other hand, a next-generation communication system is developing into the form of providing a service of transmitting and receiving large-capacity data to and from a Mobile Station (MS) at high speed. A representative example of the next-generation communication system is an Institute of Electrical and Electronics Engineers (IEEE) 802.16e communication system. The IEEE 802.16e communication system is a representative communication system using an orthogonal frequency division multiplexing (OFDM) scheme and an orthogonal frequency division multiple access (OFDMA) scheme. Now, the case where the ICI occurs in the IEEE 802.16e communication system will be described with reference to FIG. 1.
FIG. 1 is a schematic view illustrating a structure of a conventional communication system in which an interference signal occurs.
Referring to FIG. 1, the communication system includes a first cell 110, a second cell 120, a third cell 130, a first Base Station (BS) 111 for managing the first cell 110, a second BS 121 for managing the second cell 120, a third BS 131 for managing the third cell 130, a first MS 113 for receiving a service from the first BS 111, a second MS 123 for receiving a service from the second BS 121, and a third MS 133 for receiving a service from the third BS 131. The first BS 111, the second BS 121, and the third BS 131 provide the services using the same frequency resource. Since the services are provided using the same frequency resource, the ICI occurs, resulting in the fatal degradation of uplink and downlink performance.
For example, when a first signal 115 is transmitted from the first MS 113 to the first BS 111, a second signal 117 transmitted from the second MS 123 and a third signal 119 transmitted from the third MS 133 become interference signals to the first signal 115. Since the second signal 117 and the third signal 119 are interference signals that are received along with the first signal 115, the uplink performance of the first BS 111 is degraded.
Therefore, an interference signal elimination technology is needed to prevent the degradation of uplink and downlink performance.